From fe8771b8eca9a6c193877260faca60c8c19e62f3 Mon Sep 17 00:00:00 2001
From: pabr <pabr@pabr.org>
Date: Tue, 27 Mar 2018 12:29:37 +0200
Subject: [PATCH] Allow non-blocking stdin for leandvbtx real-time mode.

---
 ChangeLog.md          |  4 ++++
 src/apps/leandvbtx.cc | 13 +++++++++++++
 src/leansdr/generic.h | 14 ++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/ChangeLog.md b/ChangeLog.md
index b394c81..ee2bc12 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,4 +1,8 @@
 HEAD
+  * leandvbtx: Added real-time mode (-fill).
+  * leansdrserv: Network access to leansdr command pipelines.
+  * leaniio{rx,tx}: PlutoSDR support via libiio.
+  * leanmlmrx: Multi-channel FM demodulator.
   * leandvb: Spectrum output, JSON syntax.
   * leandvb, leandvbtx: DVB-S with non-standard constellations (with --viterbi).
   * leandvb: Support all DVB-S code rates with --viterbi.
diff --git a/src/apps/leandvbtx.cc b/src/apps/leandvbtx.cc
index 2e99765..6607ccc 100644
--- a/src/apps/leandvbtx.cc
+++ b/src/apps/leandvbtx.cc
@@ -50,12 +50,14 @@ struct config {
   float rolloff;
   float rrc_rej;
   enum { OUTPUT_F32, OUTPUT_S16 } output_format;
+  bool fill;
   bool verbose, debug;
   config()
     : constellation(cstln_lut<256>::QPSK), fec(FEC12),
       amp(1.0), agc(false),
       interp(2), decim(1), rolloff(0.35), rrc_rej(10),
       output_format(OUTPUT_F32),
+      fill(false),
       verbose(false), debug(false)
   { }
 };
@@ -167,6 +169,14 @@ void run(config &cfg) {
     fail("Output format not implemented");
   }
 
+  if ( cfg.fill ) {
+    if ( cfg.verbose ) fprintf(stderr, "Realtime mode\n");
+    tspacket blank;
+    memset(blank.data, 0, 188);
+    blank.data[0] = 0x47;
+    r_stdin.set_realtime(blank);
+  }
+
   sch.run();
   sch.shutdown();
   if ( sch.verbose ) sch.dump();
@@ -192,6 +202,7 @@ void usage(const char *name, FILE *f, int c, const char *info=NULL) {
      "  --agc                    Better regulation of output power\n"
      "  --f32                    Output 32-bit floats, range +-1.0 (default)\n"
      "  --s16                    Output 16-bit ints\n"
+     "  --fill                   Insert blank packets\n"
      "  -v                       Output debugging info at startup and exit\n"
      "  -d                       Output debugging info during operation\n"
      "  --version                Display version and exit\n"
@@ -272,6 +283,8 @@ int main(int argc, char *argv[]) {
       cfg.output_format = config::OUTPUT_F32;
     else if ( ! strcmp(argv[i], "--s16") )
       cfg.output_format = config::OUTPUT_S16;
+    else if ( ! strcmp(argv[i], "--fill") )
+      cfg.fill = true;
     else 
       usage(argv[0], stderr, 1, argv[i]);
   }
diff --git a/src/leansdr/generic.h b/src/leansdr/generic.h
index 2a4329f..8a94f99 100644
--- a/src/leansdr/generic.h
+++ b/src/leansdr/generic.h
@@ -3,6 +3,8 @@
 
 #include <sys/types.h>
 #include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
 
 #include "leansdr/math.h"
 
@@ -20,6 +22,7 @@ struct file_reader : runnable {
   file_reader(scheduler *sch, int _fdin, pipebuf<T> &_out)
     : runnable(sch, _out.name),
       loop(false),
+      filler(NULL),
       fdin(_fdin), out(_out)
   {
   }
@@ -29,6 +32,11 @@ struct file_reader : runnable {
 
   again:
     ssize_t nr = read(fdin, out.wr(), size);
+    if ( nr<0 && errno==EWOULDBLOCK && filler ) {
+      if ( sch->debug ) fprintf(stderr, "U");
+      out.write(*filler);
+      return;
+    }
     if ( nr < 0 ) fatal("read");
     if ( ! nr ) {
       if ( ! loop ) return;
@@ -52,7 +60,13 @@ struct file_reader : runnable {
     out.written(nr / sizeof(T));
   }
   bool loop;
+  void set_realtime(T &_filler) {
+    int flags = fcntl(fdin, F_GETFL);
+    if ( fcntl(fdin, F_SETFL, flags|O_NONBLOCK) ) fatal("fcntl");
+    filler = new T(_filler);
+  }
 private:
+  T *filler;
   int fdin;
   pipewriter<T> out;
 };